This invention is adapted for use with a combination of belt retractor and belt tensioner with a housing, with a belt shaft locking device having at least one locking device which can be actuated, with vehicle sensitivity and/or belt strap sensitivity, into a set of locking teeth on the housing side, and with a pre-tensioning device which acts on the belt shaft and comprises a drive wheel which can be connected to the belt shaft via the locking device in power-transmitting relationship. In this type of retractor, the drive wheel acts on a control disc as part of the vehicle sensitive and/or belt strap sensitive control system for the locking device and, as a result of the relative rotation of the control disc relatively to the belt shaft as introduced by way of the drive wheel the locking device is actuated into the power-transmitting engagement with the drive wheel.
A belt retractor combination with the aforementioned characteristics is described as a so-called power roto-pre-tensioner in WO03/082640 A1. A particular characteristic of this known belt retractor and belt pre-tensioner combination consists in the fact that no coupling is provided for coupling the drive wheel to the belt shaft and that instead of this the locking device which is needed for the self-locking belt retractor function or the correspondingly arranged locking means is used in the form of a radially displaceable blocking latch for power-transfer connection of the drive wheel with the belt shaft during the pre-tensioning operation. At the same time, the drive wheel is coupled, following triggering of the pre-tensioning device, to the housing of the belt retractor-belt tensioner combination by means of a releasable blocking latch and therefore forms, for the belt retractor function, a part of the housing for restraining the blocking forces from the belt shaft.
As the movement of the blocking latch within the framework of the self-blocking belt retractor function is carried out by an associated control disc and its vehicle-sensitive or belt-sensitive relative rotation to the belt shaft, in the known belt-retractor-belt tensioner combination, a separate trigger element is provided, which is connected with the drive wheel by means of an interference fit and which can be coupled with the control disc via inertia-controlled coupling members. If, following triggering of the pre-tensioning device, the drive wheel starts to turn in the direction of retracting the belt webbing, the trigger element which is also turning is, because of the mass inertia of its associated coupling members, coupled with the control disc and drives with its rotary direction. The relative rotation of the control disc in relation to the belt shaft which is instigated by these means leads to displacement of the blocking latch into force-transferring engagement with an inner toothing formed on the drive wheel. This means that the belt shaft is coupled to the rotating drive wheel in a power-transferring fashion.
The disadvantage is associated with the known belt retractor-belt pre-tensioner combination in that the arrangement of the additional trigger element with its allocated mass-controlled coupling members presents additional work and costs in manufacturing and mounting of these additional components, whereby such an additional coupling lengthens the response path of the pre-tensioning device for the belt shaft and can also present a function-related weak point. In a belt retractor-belt pre-tensioner combination with the above described generic characteristics, this invention simplifies the triggering of the coupling of the drive wheel to the belt shaft at the start of the rotation of the drive wheel.
The solution of this task, including advantageous forms and further developments of the invention, results from the content of the present invention.
The basic idea of the present invention is that a lever is provided which is driven by the drive wheel when it turns in the pre-tensioning direction is located so as to be capable of swiveling relative to the housing, whose free end engages with the control disc by means of its swivel movement which occurs by means of rotation of the drive wheel and thereby drives the control disc to a relative rotation in relation to the belt shaft over a part of its swivel path. The lever, after completing a swivel path serving to drive the control disc, becomes free from the control disc and the drive wheel. The invention entails the advantage that with the swivel lever, only one additional component has to be provided, which in addition is affected by the drive wheel with a forced control and by these means provides the necessary rotary movement of the control disc. A considerable simplification of the structure of the belt retractor—belt pre-tensioner combination is associated with this, and also an improvement as regards functional reliability. As the lever at the end of its function is taken out of engagement with the control disc and the drive wheel and remains in this position, the further function of the belt retractor-belt pre-tensioner combination can no longer be affected by the lever.
According to an embodiment of the invention it is provided that the pivot bearing of the lever is arranged outside the drive wheel on the housing and the lever of the drive wheel penetrates through a gap formed in its circumference. During the swivel path of the lever the drive of the control disc is engaged with its free end with an outer teeth formed on the control disc. It can also be provided that the pivot bearing of the lever is arranged in such a way that the lever, after completing its engagement movement with the control disc is pushed out of the gap in the drive wheel through the further rotation of the drive wheel.